CALL SEQUENCE...
       ggsign  GGIN INPUT OUTPUT [ -t1 VAL1 -name VAL2 -lv1 VAL3 -label VAL4 ]
 
 
      DESCRIPTION...
       ggsign - MAPS THE SIGN (-,0,+) OF EACH POINT IN A GRID
 
 
      AUTHOR  - J.D.Henderson, NOV 24/80.
      LAST REVISION: $Header: Autres-corrections-d-usages-de-MAXW-NWDS-modifs-dans-GGSIGN-SIGNAG @ 2018-06-05 17:00:06 -0400 (dugas) $
 
 
      PURPOSE - DRAWS A COMPACT MAP OF THE SIGN OF EACH GRID POINT FOR EACH
                GRID IN A GCM DIAGNOSTIC OUTPUT FILE AS REQUESTED ON CARDS.
                GRIDS MUST BE REQUESTED IN THE SAME ORDER AS THEY OCCUR IN
                THE FILE SINCE THE FILE IS SCANNED ONLY ONCE.
 
 
      INPUT FILE...
       GGIN = FILE CONTAINING GRIDS TO BE MAPPED
 
 
      INPUT PARAMETERS...
 
       NSTEP (t1)  = Selected timestep.
       NAME        = Name of the variable to look for. If name='NEXT'
                     or blank, the next grid on the file is mapped.
       LEVEL (lv1) = Selected level.
 
       LABEL       = Label (80 CHARACTERS MAXIMUM).
 
       READ( 5,5010 ) NSTEP,NAME,LEVEL
       READ( 5,5012 ) LABEL
 5010  FORMAT(10X,I10,1X,A4,I5)
 5012  FORMAT(20A4)
 
 
      EXAMPLE OF INPUT LINES...
 
    GGSIGN         6  PHI  500
          500 MB GEOPOTENTIAL
 
         0123456789012345678901234567890123456789012345678901234567890
         1         2         3         4         5         6         7
 
 
      EXIT CONDITIONS...
        0 NO PROBLEMS
        1 MISSING ARRAY ON FILE GGIN
        2 MISSING LABEL INFORMATION
        3 PREMATURE EOF ON GGIN